This invention relates to a construction of a vehicle body of means of transportation which is subjected to external pressure tending to fluctuate.
It has hitherto been usual practice to construct a vehicle body in a manner to serve the purpose of use and suit the condition of operation. Thus, a body of a railroad car has a cross-sectional shape which is substantially rectangular, and a body of an aircraft used for transporting passengers is substantially circular in cross-sectional shape.
In the case of a vehicle body of substantially square cross-sectional shape, it is possible to secure ample space above the heads of the passengers and in the vicinity of their legs, so that good riding comfort of the passengers can be obtained. However, a vehicle body of a square shape is rather low in strength with respect to fluctuations in external pressure applied thereto. It is difficult to solve this problem without increasing the weight of the vehicle body. Meanwhile, when the vehicle body has a substantially circular cross-sectional shape, its strength with respect to fluctuations in external pressure applied thereto is high. However, this type of vehicle body suffers the disadvantage that the passengers' riding comfort is impaired by the lack of a space for the passengers to move their legs freely in sitting position and stand up without their heads knocking against some objects. Any attempt to solve this problem would entail an increase in the size of the body with an attendant rise in weight. Thus, in the case of vehicle bodies of both rectangular and circular cross-sectional shape, the solutions proposed to obviate the aforesaid disadvantages have been unsatisfactory.